(iii) blue litmus solution remained blue, a green gas was evolved with sodium bicarbonate. the answer is (i) blue litmus solution turned red, a colourless gas was evolved with sodium bicarbonate. since acetic acid is an acid, it turns blue litmus solution to red just like all other acids do. sodium bicarbonate has the formula NaHCO3. the reaction with acetic acid (CH3COOH) is as follows: